Electric circuit breaker



Nov. 17, 1953 n.1. CASEY 2,659,783

ELECTRIC CIRCUIT BREAKER Filed July 1'7. 1951 5 Sheets-Sheet l Nov. 17, 1953 R. T. CASEY ELECTRIC CIRCUIT BREAKER 5 Sheets-Sheet 2 Filed July 17, 1951 l-n Illlllllllpv INVENTOR. /Qafxe Z 6435 BY Nov. 17, 1953 R. T. CASEY 2,659,783

ELECTRIC CIRCUIT BREAKER Filed July 17, 1951 5 Sheets-Sheet 3 Tirz. ll.

INVENTOR.

Nov. 17, 1953 R. T. CASEY 2,659,783

ELECTRIC CIRCUIT BREAKER Filed July 17, 1951 5 Sheets-Sheet 4 T icl. l5.

IN VEN TOR. ,6055er I my Nov. 17, 1953 R. T. cAsEY 2,659,783

ELECTRIC CIRCUIT BREKER Filed July 17. 1951 5 Shests-$heet 5 INVENTOR. /Qofe CASE# Arme/VFY Patented Nov. 17, 1953 ELECTRIC CIRCUIT BBEAKER Robert T. Casey, Bristol, Conn., assignor to General Electric Company, a corporation ot New York Application July 17, 1951, Serial No. 237,256

5 Claims. 1

It is an object of my invention to provide automatic releasing means for circuit breakers which will operate both thermally and magnetically, and which is simple and economical in construction, is easily assembled, and is dependable in operation.

Another object is to provide releasing means for circuit breakers having a thermally responsive member and a separate magnetically responsive member which coact with each other but which retain their respective original calibrations at all times.

Another object is to provide for use in circuit breakers, separate magnetic and thermal tripping means movable in relatively opposite directions to cause tripping, in such a way that the speed oi.' releasing on high overloads is proportionate to the sum of the speeds of movement of the magnetic and thermal means.

Another object is to provide a combination thermal and magnetic tripping means for circuit breakers in which the deilection of the thermal element will not be limited by the magnetic element.

Another object is to provide magnetic tripping means i'or circuit breakers which will be actuated by a magnetic iield but will not operate to cause opening of the circuit breaker until the magnetic field is reduced.

Another object is to provide magnetic tripping means for alternating current circuit breakers which will tend to cause opening oi' the breaker contacts at a point in the A.C. cycle at or near the current-zero point.

Fig. 1 is a face view of mechanism embodying one form of my invention, the parts being shown in the closed circuit position.

Fig. 2 is a similar view of the mechanism of Fig. 1 shown in the automatic tripped position.

Fig. 3 is a vertical sectional view taken on the general plane of the line I--I of Fig. 1.

Fig. 4 is a side view oi' the cradle or tripping member.

Fig. 5 is an edge view of the cradle oi Fig. 4.

Fig. 6 is an edge view of the armature of the magnetic release device.

Fig. 7 is a side view of the same.

Fig. 8 is a plan view of the same.

Fig. 9 is a perspective view of the same.

Fig. 10 is a face view of a modified form o! 2 mechanism, parts being shown in closed circuit position.

Fig. 11 is a fragmentary sectional view on the plane of the line I I-I I of Fig. 10.

Fig. l2 is a face view of the cradle 0r tripping member of the form shown in Fig. 10.

Fig. 13 is an edge view of the device of Fig. 12.

Fig. 14 is a view similar to.Fig. 13 but looking at the cradle from the opposite side.

Fig. l5 is a face view oi.' another modified form of mechanism involving my invention, the parts being shown in the closed circuit position.

Fig. 16 is a face view of the cradle or tripping member of the form shown in Fig. 15.

Fig. 17 is an edge view oi' the same.

Fig. 18 is a fragmentary perspective view showing the connection between the bimetal member. the tripping or cradle member and the arm of the magnetic release device of Fig. 15.

Fig. 19 is a perspective view of the armature member of the magnetic device of Fig. 15.

Fig. 20 is a detail view of the end of the bimetal member.

Fig. 2l is a face view showing a modified form of mechanism' embodying my invention, the parts being shown in the closed circuit position.

Fig. 22 is a perspective view oi the latching member of Fig. 21, on an enlarged scale. It will be understood that the mechanism will be enclosed in a suitable housing preferably part is substantially the mirror image of the other.

The circuit terminals 2 and 3 are suitably supported in the housing. Stationary contact 4 is connected to the terminal 2. A bimetal strip 5 is secured at 6 t0 a bracket 1 which extends inwardly from the terminal 3. A Calibrating screw 8 is suitably mounted in the housing. A movable switch member 9 is connected by a flexible lead I0 to the movable part of the bimetal strip. A cradle or trip member II is hinged at I2 in the housing and provides a bearing I 3 for the switch member 9.

A manually operable member I4 is secured to the outer end of a lever I5 which is hinged in a groove I6 in the inner wall of the housing. A

3 spring I1 is connected at I5 to the actuating lever I5 and connected at its lower end to the switch arm 9 at I9.

To open the circuit manually from the closed position of Fig. l, the actuating or nger piece I4 is moved to the right so that the upper end ol' the spring I1 is carried to the right of the hinge Il whereupon the switch member snaps quickly from closed to open circuit position.

Normally the cradle or trip arm II is held in the position of Fig. 1 by latching means cooperating between the bimetal member 5 and the long arm oi' the cradle. A latching member 2i is hinged or pivotally mounted at 22 on the lower end of the cradle or tripping arm II and is normally drawn by the spring 25 against the abut ment 2l, the spring being hooked over the edge 25 and connected at 25 to the armature member 21.

In case of a prolonged relatively light overload current, the bimetal strip 5 warps to the right as viewed in Fig. 1 until the latch 2| is disconnected from the bimetal whereupon the tension of the spring I1 draws the switch member 9 to the right and tilts the tripping arm Il from the position of Fig. 1 to the position ot Fig. 2. The lug 28 carried by the tripping arm serves to limit the movement of the bimetal strip.

It will be observed that as shown in Figs. 6-9, latch 2| has a centrally located opening 2i o! width slightly greater than the width of the end of the bimetal strip 5. This permits the pivot point 22 to be in direct line with the bimetal 5, as in Fig. 1, without interfering with the tripping action as shown in Fig. 2.

To reset the breaker from an automatic release as above described, it is merely necessary to move the linger piece of the actuating member to the right whereupon the lug 28 on the actuating member engages the edge 35 on the cradle. Continued movement of the finger piece to the right tilts the cradle back to the position of Fig. l during which movement the lug 2| slides upon the bimetal strip until it engages the tip of the bimetal strip (see Fig. l). 'I'he circuit may then be closed in the usual manner.

In order to break the circuit in case oi' a heavy sudden overload current, I provide magnetic means including a magnetic pole piece 5I which has an armature 21, previously described as a part o! the latching mechanism. In case or a heavy overload, the amature is attracted and drawn down from the position of Fig. 1 and thereby the member 2l is retracted from the end ot the bimetal strip 5 leaving the spring I1 free to throw the cradle into the position o! Fig. 2. As above described, the switch arm l is drawn from the closed to the open circuit position where the switch arm l abuts against a stop l2.

It will be noted that in the automatic opening of the circuit due to a, prolonged relatively light overload, the tripping member is released by the movement of the bimetal strip to the right in Fig. l. and in case oi' a sudden heavy overload the release is brought about by attraction oi' the amature 21 which tilts the lug 2| to the left so that the trip arm is free to turn about the pivot I2.

The cord or braid I may be held in place between the pole pieces by a clamp plate I0' which should be formed oi' non-magnetic material.

On Sheet 3 of the drawings, I have shown mechanism embodying a modified form o!v my invention, in which the tripping cradle I is hinged at l5. The switch member l1 is hinged at 3B to the cradle and coacts with the stationary contact 39. The actuating member Il is pivoted at 4I. A throwing spring 42 connects the actuating member at 53 to the switch member 51 at 44. The bimetal strip l5 is lxed at 45 and is connected by a flexible conductor 51 to the switch member 31. The magnet in this case has a portion 50 which is integral with the lower end of the tripping arm. The armature 5I is pivoted at 52 and has a projection 53 which normally abuts against the end o! the bimetal member 45. A spring 54 is connected to a bridge piece 55 at its upper end and at its lower end the spring is connected to the armature at 55. The spring normally draws the armature against the' abutment 51. The lug 55 Serves to limit the movement of the bimetal strip.

In case of a moderate overload, the bimetal strip warps toward the right as viewed in Fig. l0 which disconnects it from the latching projection 53, thus permitting the tripping lever to swing anti-clockwise about its pivot 35. As the pivot point Il passes the line o! tension of the spring I2, the switch member l1 is thrown to the open circuit position.

In case of a sudden heavy overload in the circuit, the armature 5I is drawn toward the ileld piece 55 of the magnet so that the latching member 53 is disengaged from the bimetal strip 45 so that the tripping member is free to operate and open the circuit as Just described.

To reset the switch member after an automatic release, the ringer piece is moved to the right as viewed in Fig. 10 whereupon the lug 55 on the actuating lever engages the edge 5I of the cradle and tilts the cradle clockwise about its pivot 25. The end of abutment 5l is then drawn down along the side of the bimetal strip 55 until the latch member 5l snaps beneath the end ot the bimetal strip whereupon the switch is in open circuit position and free to be actuated in the usual manner.

In the form of mechanism shown on Sheet 4. the tripping member or cradle 55 is pivoted at 55. The switch member l1 is hinged at 5l to the cradle and coacts in the usual manner with the stationary contact 55. Spring 15 connects the switch member to the actuating member at 1I. The bimetal strip 12 is supported as previously described and has shoulders 15 which normally stand in the path oi movement of the latch members 14 on the opposite sides ci' the tripping member or cradle 55. A flexible conductor 15 lies between the sides of the tield piece 15 and connects the bimetal strip with the movable contact. 'I'he armature 11 is pivoted at 1l in the end oi' the cradle and has a tongue 15. A spring 8l connects a lug Il on the cradle with the armature at 52, and draws the armature against the stop I3. The magnet armature has a central lanced out portion which iorms the tongue 1l.

In case of a heavy overload the armature 11 tilts and the tongue 1I pushes the tip of the bimetal of! of the latch member 15 which leaves the tripping member or cradle 55 free to move to the open circuit position.

In order to bring the spacing of the latching tips down to slightly less than the width of the bimetal strip, the side pieces of the cradle are offset at 55'.

In the form shown in Fig. 21, the tripping member or cradle 55 is hinged at Il and supports the movable switch member 51 at 55. The acs,sso,rsa

tuating member is hinged at 00 in the housing (not shown). The spring 0| connects theactuating member with the switch member. The bimetal strip 02 is supported at 0I and its tip connected to a flexible conductor 0I which is connected to the movable switch member 01. The normal closed circuit extends from terminal 0l, through bracket 00, bimetal strip 9 2, conductor 04, switch member 01, stationary contact l1 to terminal 90. The long arm of the tripping member or cradle l5 carries the pivot 09 of the latching member. This latching member has a lug |00 and an armature I0l adapted to coact with the magnet field piece |02. The spring |00 connects the cradle I0 with the latching member and biases the armature against the stop |04. The latch piece |05 is hinged at |00 to the housing (not shown). This piece |05 has an extension |01 which forms an abutment for the latch member |00. This piece |05 also has a toe |00 which extends adjacent the tip of the bimetal strip 02. When the bimetal strip is warped by heat to move toward the right it will withdraw the latch member |01 from the part |00 and allow the spring 0| to throw the parts to open circuit position. The spring H0 pushes the toe |00 against the bimetal strip to return it to its normal position when cooled, so that the part |01 will be brought back in proper position to receive the latching engagement of the mechanism for resetting the switch after an automatic release.

In case of a sudden heavy overload, the magnet is energized and draws the armature IOI downwardly thus moving the latch part |00 to disengage it from the latch part |01, thus permitting the cradle to move to open the circuit as in themanner previously described.

This is a partial continuation of application Serial Number 91,085 iiled May 3, 1949, now Patent No. 2,573,307 issued October 30, 1951.

I claim:

1. A circuit breaker having circuit making and breaking mechanism and a housing therefor, a

trip member for said mechanism biased for movement to an open circuit position, a latch member movably mounted on said trip member and movable with said trip member, a bimetal member normally engaging said latch member so as to hold said trip member against its bias in a closed circuit position, means for heating said bimetal member in response to the current in the circuit breaker so as to cause said bimetal member to move out of engagement with said latch member upon the occurrence of a light overload current thereby to release said trip member, an armature connected to said latch member, and magnetic means iixed in said housing responsive to the current in the circuit breaker for moving said armature and said latch member upon the occurrence of a heavy overload current thereby to move said latch member out o! engagement with said bimetal member and release said trip member.

2. A circuit breaker having circuit making and breaking mechanism and a housing therefor, a trip member for said mechanism biased for movement to an open circuit position, a combined armature and latch member movably mounted on said trip member and movable with said trip member, a bimetal member normally engaging said latch member so as to hold said trip member against its bias in a closed circuit position, means for heating said bimetal member in response to the current in the circuit breaker so as to' causel said bimetal member to moveout o! engagement with said latch member upon the occurrence of a light overload current thereby to release said trip member, and magnetic means iixed in said housing `responsive to the current in the circuit breaker for attracting said armature upon the occurrence of a heavy overload current thereby to move said latch member out of engagement with said bimetal member and release said trip member,

3. A circuit breaker having circuit making and breaking mechanism and a housing therefor, a pivotally mounted trip arm for said mechanism biased for movement to an open circuit position. a combined armature and latch member pivotally mounted on the movable end of said trip arm and movable with said trip arm, a bimetal member normally engaging said latch member so as to hold said trip arm against its bias in a closed circuit position, means for heating said bimetal member in response to the current in the circuit breaker so as to cause said bimetal member to move out of engagement with said latch member upon the occurrence of a light overload current thereby to release said trip arm, and magnetic meansv iixed in said housing responsive to the current in the circuit breaker for attracting said armature upon the occurrence of a heavy overload current thereby to move said latch member out of engagement with said bimetal member and release said trip member.

4. A circuit breaker comprising a housing, a pivoted actuating member, a cradle pivotally mounted at one end, a switch arm provided with a movable switch contact pivoted on said cradle at a point, intermediate its ends, a cooperating iixed switch contact, a spring connecting said actuating member and said switch member movable by said actuating member to snap said switch arm to a closed circuit position to engage said contacts and to an open circuit position to disengage said contacts, said spring applying a force to said switch member to bias said cradle for movement about its pivot to a. predetermined position in which said switch arm is in an open circuit position, a latch member pivotally mounted on the movable end of said cradle, a bimetal member normally engaging said latch member thereby to hold said cradle in a predetermined normal switch operating positionI means for heating said bimetal member in response to the current in said contacts so as to cause said bimetal member to move out of engagement with said latch member upon the occurrence of alight overload current thereby to release said cradle, an armature connected to said latch member, and magnetic means tlxed in said housing responsive to the current in said contacts for attracting said armature to move said latch member about its pivot out of engagement with said bimetal member upon the occurrence of a heavy overload current thereby to release said cradle.

5. A circuit breaker comprising a housing, a pivoted actuating member, a cradle pivotally mounted at one end, a switch arm provided with a movable switch contact pivoted on said cradle at a point intermediate its ends, a cooperating fixed switch contact, a tension spring connecting said actuating member and said switch member movable by said actuating member to snap said switch arm to a closed circuit position to engage said contacts and to an open circuit position to disengage said contacts, said spring applying a force to said switch member to bias said cradle for movement about its pivot to a predetermined position in which said switch arm is in an open circuit position, a combined latch member and amature pivotally mounted on the movable end oi' said cradle, a spring ifor holding said latch member in a predetermined position relative to said cradle,a bimetal member normally engaging an end ot said latch member thereby to hold said cradle in a predetermined normal switch operating position, means for heatins said bimetal member in response to the current in said contacts so as to cause said bimetal member to move out of engagement with said' and magnetic means fixed 1n said housing responsive to the current in said contacts for attracting said amature to move said latch member about its pivot out of engagement with said bimetal member upon the occurrence of a heavy overload current thereby to release said cradle.

ROBERT T. CASEY.

References Cited in the me of this patent UNITED STATES PATENTS Dyer Feb. 20, 1945 

